This is a multicenter trial where Herceptin will be administered weekly until disease progression. Gemcitabine will be administered for seven weeks followed by a restaging CT scan of the abdomen on the eighth week. Patients with stable or responding disease will continue on with treatment. Thereafter, patients will receive gemcitabine, once weekly, for three consecutive weeks out of every four week cycle and Herceptin, once weekly, until disease progression. Up to ten patients will be enrolled on this study at the University of Pittsburgh Cancer Institute. Approximately 45 patients will be entered on the study across the United States. The specific aim of this study is to determine the response rate, toxicities and survival of patients with metastatic pancreatic cancers that overexpress HER-2/neu, after administration of gemcitabine and Herceptin.